EMBEDDED SENSOR FABRICATION
Nanojet (formerly MycroJet) has been used to fabricate direct write sensors on metal parts. Temperature, strain, proximity, and continuity sensors are printed directly onto the part, or sensors are printed onto a flexible polymer that is attached to the part. Electrical measurements show conductive traces with resistances of a few ohms/cm. Various patterns are printed to form sensors. A data acquisition system is used to take resistance measurements as a function of time, measuring and recording the sensor response.
A three-layer temperature/strain sensor printed on a Nylon washer.
IDS employs practical knowledge in the interrelated areas of ink formulation, microfluidics, surface physics and chemistry, and materials processing to develop the Liquid Jet (LJ) electronic printing technology. The underlying principle of LJ is liquid filament printing, where various structures are deposited from a continuous liquid filament, with typical print speeds in excess of 100 mm/s. LJ enables Single Filament Deposition and Coaxial Filament Deposition.
Many Liquid Jet inks are internally formulated to reduce or eliminate nozzle clogging, and to wet glass, plastic, and metal substrates. The Liquid Jet process offers 100 percent ink utilization, without ink recycling or ink degradation.
A microfluidic flow cell is used to produce hydrodynamic focusing of a core liquid (ink) by a sheath liquid. The sheath liquid can be sacrificial or non-sacrificial. Sacrificial sheath liquids are evaporated in-flight and after deposition onto the substrate.
SURFACE PHYSICS AND CHEMISTRY
Surface Physics and Surface Chemistry are used for substrate preparation and modification, so that optimized conditions for liquid filament deposition are obtained. Of particular importance are sheath and ink surface tension, substrate cleanliness, substrate surface energy, liquid jet temperature, and substrate temperature.
Most Liquid Jet inks require post processing in the form of heating. Typical heating processes are thermal or photonic, and drive the deposited structure to its final physical and electrical state.